Water-soluble UV-absorbing compounds and uses thereof

ABSTRACT

Described herein are dimethyl acetal-containing UV-absorbing compounds and their uses in preparing UV-absorbing polyvinyl alcohol prepolymers suitable for producing UV-absorbing contact lenses capable of blocking ultra-violet (“UV”) radiation and optionally (but preferably) violet radiation with wavelengths from 380 nm to 440 nm, thereby protecting eyes to some extent from damages caused by UV radiation and potentially from violet radiation. This invention also provides a UV-absorbing polyvinyl alcohol prepolymer.

This application claims the benefits under 35 USC § 119 (e) of U.S.provisional application No. 62/261,925 filed Dec. 2, 2015, incorporatedby reference in its entirety.

This invention is related to water-soluble dimethyl acetal-containingcompounds capable of absorbing ultra-violet (UV) radiation andoptionally high-energy-violet (HEVL) radiation and their uses forproducing water-soluble actinically-crosslinkable polyvinyl alcoholscapable of absorbing UV and optionally HEVL radiations. In addition, theinvention provides a method for making hydrogel contact lenses capableof blocking ultra-violet (“UV”) radiation and optionally (butpreferably) violet radiation with wavelengths from 380 nm to 440 nm.

BACKGROUND

Most commercially-available non-silicone hydrogel contact lenses areproduced according to a conventional cast molding technique involvinguse of disposable plastic molds and a mixture of vinylic monomers andcrosslinking agents. There are several disadvantages with theconventional cast-molding technique. For example, a traditionalcast-molding manufacturing process often includes lens extraction inwhich unpolymerized monomers must be removed from the lenses by using anorganic solvent. Use of organic solvents can be costly and is notenvironmentally friendly. In addition, disposable plastic moldsinherently have unavoidable dimensional variations, because, duringinjection-molding of plastic molds, fluctuations in the dimensions ofmolds can occur as a result of fluctuations in the production process(temperatures, pressures, material properties), and also because theresultant molds may undergo non-uniformly shrinking after the injectionmolding. These dimensional changes in the mold may lead to fluctuationsin the parameters of contact lenses to be produced (peak refractiveindex, diameter, basic curve, central thickness etc.) and to a lowfidelity in duplicating complex lens design.

The above described disadvantages encountered in a conventionalcast-molding technique can be overcome by using the so-calledLightstream Technology™ (CIBA Vision), which involves (1) a lens-formingcomposition being substantially free of monomers and comprising asubstantially-purified, water-soluble prepolymer withethylenically-unsaturated groups, (2) reusable molds produced in highprecision, and (3) curing under a spatial limitation of actinicradiation (e.g., UV), as described in U.S. Pat. Nos. 5,508,317,5,583,163, 5,789,464, 5,849,810, 6,800,225, and 8,088,313. Lensesproduced according to the Lightstream Technology™ can have highconsistency and high fidelity to the original lens design, because ofuse of reusable, high precision molds. In addition, contact lenses withhigh quality can be produced at relatively lower cost due to the shortcuring time, a high production yield, and free of lens extraction and inan environmentally friendly manner because of use of water as solventfor preparing lens formulations.

However, the Lightstream Technology™ has not been applied to makecontact lenses capable of absorbing ultra-violet (UV) lights (between280 nm and 380 nm) and optionally high-energy violet lights (HEVL)(between 380 nm and 440 nm), largely because of the lack ofwater-soluble polymerizable UV-absorbers which can be incorporated intothe polymer matrix of a contact lens made from a water-based lensformulation. Examples of known polymerizable UV-absorbers includeNorbloc 7966 (2-(2′-hydroxy-5′-methacryloxyethylphenyl)benzotriazole),4-acryloylethoxy-2-hydroxybenzophone,2-(2-hydroxy-5-methacrylamidophenyl)-5-methoxybenzotriazole (UV6),2-Hydroxy-4-methacryloyloxybenzophenone (UV7),2-(2′-hydroxy-5′-acryloylpropyl-3′-tert-butyl-phenyl)-5-methoxy-2H-benzotriazole(UV16A), and other benzotriazole-containing UV-absorbing vinyl monomersdescribed in U.S. Pat. Nos. 4,612,358, 4,528,311, and 7,803,359 (hereinincorporated by reference in their entireties). Examples of UV/HEVLinclude2-(5-Chloro-2H-Benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-ethenylphenoland2-(1,1-dimethylethyl)-4-[3-(4-ethenylphenyl)methoxy]propoxy-6-(5-methoxy-2H-benzotriazol-2-yl)-phenol.Additional examples of UV/HEVL absorbers disclosed in U.S. Pat. Nos.8,153,703, 8,232,326, 4,716,234, and 8,585,938 (herein incorporated byreferences in their entireties). But, those available UV-absorbers andUV/HEVL-absorbers are insoluble in water and cannot be used in theproduction of contact lenses from an aqueous lens formulation accordingto the Lightstream Technology™.

Therefore, there are still needs for a new water-soluble UV absorber ora new water-soluble UV/HEVL absorber for making UV-absorbing orUV/HEVL-absorbing contact lenses from an aqueous lens formulationaccording to the Lightstream Technology™.

SUMMARY

In one aspect, the invention provides an UV-absorbing reactive compoundcomprising a moiety of benzophenone or benzotriazole and a dimethylacetal or diethyl acetal group.

In another aspect, the invention provides a water-soluble,actinically-crosslinkable polyvinyl alcohol prepolymer comprisingethylenically unsaturated groups and UV-absorbing moieties derived froman UV-absorbing reactive compound of the invention.

In a further aspect, the invention provides a method for producingUV-absorbing contact lenses from an aqueous lens formulation comprisingat least one water-soluble, actinically-crosslinkable polyvinyl alcoholprepolymer of the invention.

The invention provides in a still further aspect hydrogel contact lensesobtained according to a method of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows the UV spectrum of a preferred water-soluble UV absorber ofthe invention in phosphate buffer (pH˜7, 12.5 mM phosphate in 1:1Water:n-propanol).

FIG. 2 shows the UV spectrum of another preferred water-soluble UVabsorber of the invention in phosphate buffer (pH˜7, 12.5 mM phosphatein 1:1 Water:n-propanol).

FIG. 3 shows the UV spectrum of a further preferred water-soluble UVabsorber of the invention in phosphate buffer (pH˜7, 12.5 mM phosphatein 1:1 Water:n-propanol).

DETAILED DESCRIPTION

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Generally, the nomenclatureused herein and the laboratory procedures are well known and commonlyemployed in the art. Conventional methods are used for these procedures,such as those provided in the art and various general references. Wherea term is provided in the singular, the inventors also contemplate theplural of that term. The nomenclature used herein and the laboratoryprocedures described below are those well-known and commonly employed inthe art.

“About” as used herein means that a number referred to as “about”comprises the recited number plus or minus 1-10% of that recited number.

“Optional” or “optionally” means that the subsequently described eventor circumstance can or cannot occur, and that the description includesinstances where the event or circumstance occurs and instances where itdoes not.

A “contact Lens” refers to a structure that can be placed on or within awearer's eye. A contact lens can correct, improve, or alter a user'seyesight, but that need not be the case.

As used in this application, the term “hydrogel” or “hydrogel material”refers to a crosslinked polymeric material which is insoluble in water,but can hold at least 10 percent by weight of water in itsthree-dimensional polymer networks (i.e., polymer matrix) when it isfully hydrated.

A “vinylic monomer” refers to a compound that has one soleethylenically-unsaturated group.

The term “soluble”, in reference to a compound or material in a solvent,means that the compound or material can be dissolved in the solvent togive a solution with a concentration of at least about 0.1% by weight atroom temperature (i.e., from about 20° C. to about 30° C.).

The term “insoluble”, in reference to a compound or material in asolvent, means that the compound or material can be dissolved in thesolvent to give a solution with a concentration of less than 0.005% byweight at room temperature (as defined above).

The term “ethylenically unsaturated group” is employed herein in a broadsense and is intended to encompass any groups containing at leastone >C═C< group. Exemplary ethylenically unsaturated groups includewithout limitation (meth)acryloyl

allyl, vinyl (—CH═CH₂), 1-methylethenyl

styrenyl, or the likes.

The term “(meth)acrylamide” refers to methacrylamide and/or acrylamide.

The term “(meth)acrylate” refers to methacrylate and/or acrylate.

A “hydrophilic vinylic monomer”, as used herein, refers to a vinylicmonomer which can be polymerized to form a homopolymer that iswater-soluble or can absorb at least 10 percent by weight of water.

A “hydrophobic vinylic monomer” refers to a vinylic monomer which can bepolymerized to form a homopolymer that is insoluble in water and canabsorb less than 10 percent by weight of water.

“UVA” refers to radiation occurring at wavelengths between 315 and 380nanometers; “UVB” refers to radiation occurring between 280 and 315nanometers; “Violet” refers to radiation occurring at wavelengthsbetween 380 and 440 nanometers.

“UVA transmittance” (or “UVA % T”), “UVB transmittance” or “UVB % T”,and “violet-transmittance” or “Violet % T” are calculated by thefollowing formula

${{UVA}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{Average}\mspace{14mu}\%\mspace{14mu}{Transmission}\mspace{14mu}{between}\mspace{14mu} 315\mspace{14mu}{and}\mspace{14mu} 380\mspace{14mu}{nm}}{{Luminescence}\mspace{14mu}\%\mspace{14mu} T} \times 100}$${{UVB}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{Average}\mspace{14mu}\%\mspace{14mu}{Transmission}\mspace{14mu}{between}\mspace{14mu} 280\mspace{14mu}{and}\mspace{14mu} 315\mspace{14mu}{nm}}{{Luminescence}\mspace{14mu}\%\mspace{14mu} T} \times 100}$${{Violet}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{Average}\mspace{14mu}\%\mspace{14mu}{Transmission}\mspace{14mu}{between}\mspace{14mu} 380\mspace{14mu}{and}\mspace{14mu} 440\mspace{14mu}{nm}}{{Luminescence}\mspace{14mu}\%\mspace{14mu} T} \times 100}$in which is Luminescence % T is determined by the following formulaLuminescence % T=Average % Transmission between 780-380 nm.

As used in this application, the term “macromer” or “prepolymer” refersto a medium and high molecular weight compound or polymer that containstwo or more ethylenically unsaturated groups. Medium and high molecularweight typically means average molecular weights greater than 700Daltons.

As used in this application, the term “vinylic crosslinker” refers to acompound having at least two ethylenically unsaturated groups. A“vinylic crosslinking agent” refers to a vinylic crosslinker having amolecular weight of about 700 Daltons or less.

As used in this application, the term “polymer” means a material formedby polymerizing/crosslinking one or more monomers or macromers orprepolymers.

As used in this application, the term “molecular weight” of a polymericmaterial (including monomeric or macromeric materials) refers to theweight-average molecular weight unless otherwise specifically noted orunless testing conditions indicate otherwise.

The term “alkyl” refers to a monovalent radical obtained by removing ahydrogen atom from a linear or branched alkane compound. An alkyl group(radical) forms one bond with one other group in an organic compound.

The term “alkylene divalent group” or “alkylene diradical” or “alkyldiradical” interchangeably refers to a divalent radical obtained byremoving one hydrogen atom from an alkyl. An alkylene divalent groupforms two bonds with other groups in an organic compound.

The term “alkyl triradical” refers to a trivalent radical obtained byremoving two hydrogen atoms from an alkyl. A alkyl triradical formsthree bonds with other groups in an organic compound.

The term “alkoxy” or “alkoxyl” refers to a monovalent radical obtainedby removing the hydrogen atom from the hydroxyl group of a linear orbranched alkyl alcohol. An alkoxy group (radical) forms one bond withone other group in an organic compound.

In this application, the term “substituted” in reference to an alkyldiradical or an alkyl radical means that the alkyl diradical or thealkyl radical comprises at least one substituent which replaces onehydrogen atom of the alkyl diradical or the alkyl radical and isselected from the group consisting of hydroxy (—OH), carboxy (—COOH),—NH₂, sulfhydryl (—SH), C₁-C₄ alkyl, C₁-C₄ alkoxy, C₁-C₄ alkylthio(alkyl sulfide), C₁-C₄ acylamino, C₁-C₄ alkylamino, di-C₁-C₄ alkylamino,halogen atom (Br or Cl), and combinations thereof.

A “photoinitiator” refers to a chemical that initiates free radicalcrosslinking/polymerizing reaction by the use of light.

In this application, a “reactive UV-absorbing compound” refers to acompound comprising a dimethyl acetal or diethyl acetal group

and a UV-absorbing moiety (benzophenone or benzotriazole moiety) whichcan absorb or screen out UV radiation in the range from 200 nm to 400 nmas understood by a person skilled in the art.

A “spatial limitation of actinic radiation” refers to an act or processin which energy radiation in the form of rays is directed by, forexample, a mask or screen or combinations thereof, to impinge, in aspatially restricted manner, onto an area having a well-definedperipheral boundary. A spatial limitation of UV radiation is obtained byusing a mask or screen having a radiation (e.g., UV and/or visiblelight) permeable region, a radiation (e.g., UV and/or visible light)impermeable region surrounding the radiation-permeable region, and aprojection contour which is the boundary between theradiation-impermeable and radiation-permeable regions, as schematicallyillustrated in the drawings of U.S. Pat. No. 6,800,225 (FIGS. 1-11), andU.S. Pat. No. 6,627,124 (FIGS. 1-9), U.S. Pat. No. 7,384,590 (FIGS.1-6), and U.S. Pat. No. 7,387,759 (FIGS. 1-6), all of which areincorporated by reference in their entireties. The mask or screen allowsto spatially projects a beam of radiation (e.g., UV radiation and/orvisible radiation) having a cross-sectional profile defined by theprojection contour of the mask or screen. The projected beam ofradiation (e.g., UV radiation and/or visible radiation) limits radiationimpinging on a lens formulation located in the path of the projectedbeam from the first molding surface to the second molding surface of amold. The resultant contact lens comprises an anterior surface definedby the first molding surface, an opposite posterior surface defined bythe second molding surface, and a lens edge defined by the sectionalprofile of the projected UV and/or visible beam (i.e., a spatiallimitation of radiation). The radiation used for the crosslinking isradiation energy, especially UV radiation (and/or visible radiation),gamma radiation, electron radiation or thermal radiation, the radiationenergy preferably being in the form of a substantially parallel beam inorder on the one hand to achieve good restriction and on the other handefficient use of the energy.

The term “modulus” or “elastic modulus” in reference to a contact lensor a material means the tensile modulus or Young's modulus which is ameasure of the stiffness of a contact lens or a material. The moduluscan be measured using a method in accordance with ANSI Z80.20 standard.A person skilled in the art knows well how to determine the elasticmodulus of a silicone hydrogel material or a contact lens. For example,all commercial contact lenses have reported values of elastic modulus.

In general, the invention is directed to a class of dimethylacetal-containing UV-absorbing compounds which are soluble in water dueto the presence of hydrophilic groups, and can be used, in combinationwith a dimethyl acetal- or diethyl acetal-containing vinylic monomer(e.g., (meth)acrylamidoacetaldehyde dimethyl or diethyl acetal), tochemically modified a polyvinyl alcohol polymer to form a water-soluble,actinically-crosslinkable polyvinyl alcohol prepolymer capable ofabsorbing UV radiation and optionally HEVL radiation. Resultantpolyvinyl alcohol prepolymers are useful for making UV-absorbinghydrogel contact lenses, in particularly, according to the LightstreamTechnology™.

In one aspect, the present invention provides an acetal-containing,UV-absorbing compound of any one of formula (I) to (V)

in which:

-   -   R^(a) is CH₃ or C₂H₅;    -   R^(o) is H or CH₃;    -   R₁, R₂ and R₂′ independent of one other are H, CH₃, CCl₃, CF₃,        Cl, Br, NR′R″ in which R′ and R″ independent of each other are H        or C₁-C₄ alkyl, OH, or OCH₃;    -   R₁′ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br,        NR′R″ in which R′ and R″ independent of each other are H or        C₁-C₄ alkyl, OH, OCH₃, SO₃H, or SO₃ ⁻Na⁺;    -   R₃ and R₄ independent of each other are H or a first hydrophilic        group which is

-   -    provided that at least one of R₃ and R₄ is the first        hydrophilic group;    -   r1 is an integer of 1 to 8 (preferably 3 to 6);    -   n1 is an integer of 2 to 20 (preferably 3 to 15, more preferably        4 to 10);    -   R₅ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or        —CONH—C₂H₄—(OC₂H₄)_(n1)—OH;    -   one of R₆ and R₇ is H or a second hydrophilic group which is

-   -    while the other of R₆ and R₇ is

-   -   R₈ is CH₃, C₂H₅,

-   -   R₉ is SO₃Na,

-   -   R₉′ is H, SO₃Na,

-   -   R₁₀ is methyl or ethyl;    -   L1 is a linkage of

-   -   L2 is a linkage of

-   -   L3 is a linkage of

-   -    and    -   X1 is O or NR^(o).

Examples of preferred an acetal-containing, UV-absorbing compound offormula (I) include without limitation:

in which R^(a) is methyl or ethyl, R₁ and R₂ independent of each otherare H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″, OH, or OCH₃, in which R′ and R″independent of each other are H, methyl or ethyl.

Examples of preferred an acetal-containing, UV-absorbing compound offormula (II) include without limitation:

in which: R^(a) is methyl or ethyl; R₁ and R₂ independent of each otherare CH₃, CCl₃, CF₃, Cl, Br, NR′R″, OH, or OCH₃; R′ and R″ independent ofeach other are H, methyl or ethyl; R₃ and R₄ independent of each otherare

R₁₀ is methyl or ethyl.

Examples of preferred an acetal-containing, UV-absorbing compound offormula (III) include without limitation:

in which: R^(a) is methyl or ethyl; R₁ and R₂ independent of each otherare CH₃, CCl₃, CF₃, Cl, Br, NR′R″ OH, or OCH₃; in which R′ and R″independent of each other are H or C₁-C₄ alkyl; R₈ is CH₃, C₂H₅,

R₁₀ is methyl or ethyl; and r1 is an integer of 3 to 6.

Examples of preferred an acetal-containing, UV-absorbing compound offormula (IV) include without limitation:

in which R^(a) is methyl or ethyl; R^(o) is H or CH₃; R₁ and R₂independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″ in whichR′ and R″ independent of each other are H or C₁-C₄ alkyl, OH, or OCH₃.

Examples of preferred an acetal-containing, UV-absorbing compound offormula (V) include without limitation:

in which R^(a) is methyl or ethyl, r1 is an integer of 3 to 6, and Z═CH₃or COOH.

An acetal-containing UV-absorbing compound of formula (I) defined abovecan be prepared according to procedures illustrated in Scheme 1:

An acetal-containing UV-absorbing compound of formula (II) defined abovecan be prepared according to procedures illustrated in Scheme 2:

An acetal-containing UV-absorbing compound of formula (III) definedabove can be prepared according to procedures illustrated in Scheme 3:

It is understood that in the 2^(nd) step of Scheme 1 or 2,2,2-dimethoxyethanamine can be substituted with1,1-dimethoxy-N-methylethanamine. The 3^(rd) step of Scheme 2 can bealtered to form a phosphocholine group by reacting an alkyl alkylenephosphate (e.g., methyl ethylene phosphate, ethyl ethylene phosphate,methyl propylene phosphate, or ethyl propylene phosphate), instead of1,3-propane sultone, under conditions known to a person skilled in theart (Makromol. Chem., Rapid Commun. 3, 457-459 (1982). It is alsounderstood that Scheme 3 can be modified by replacing1,1-dimethoxy-N,N-dimethylethanamine with1,1-dimethoxy-N-methylethanamine and then by adding one step of reactingthe product of the 3^(rd) step with 1,3-propane sultone or an alkylalkylene phosphate (e.g., methyl ethylene phosphate, ethyl ethylenephosphate, methyl propylene phosphate, or ethyl propylene phosphate)under conditions known to a person skilled in the art to form a compoundof formula (III) with R₈ is a radical other than methyl.

Any 2-hydroxy-2′-carboxy benzophenones with substituents on either orboth benzene rings can be used in the preparation of a compound offormula (I), (II) or (III). A person knows how to prepare a2-hydroxy-2′-carboxy benzophenones with substituents from a substitutedor unsubstituted phthalic anhydride and a substituted or unsubstitutedphenol (see, e.g., U.S. Pat. No. 5,925,787, herein incorporated inreference in its entirety).

It is understood that in the 2^(nd) step of Scheme 2 any 3- and4-substituted phthalic anhydride can be used to react with any mono- ordi-substituted phenol to obtain a compound of formula (I), (II) or(III). Various 3- and 4-substituted phthalic anhydrides are commerciallyavailable or can be prepared according to the procedures described in J.Chem. Soc., Perkin Trans. (1977), 1: 2030-2036 (herein incorporated byreference in its entirety).

An acetal-containing UV-absorbing compound of formula (IV) defined abovecan be prepared according to procedures illustrated in any one ofSchemes 4 to 7:

It is understood that in Scheme 4, a starting benzotriazole compoundwith a carboxy-containing substituent can also be prepared from besubstituted with one in which the substituent carboxyethyl group isreplaced with allyl group can be substit

An acetal-containing UV-absorbing compound of formula (V) defined abovecan be prepared according to procedures illustrated in Scheme 8 or 9:

Any benzotriazoles with substituents can be used in the preparation of acompound of formula (IV) or (V). A person knows how to prepare abenzotriazole with different substituents according to a known procedure(see, e.g., U.S. Pat. No. 8,262,948, herein incorporated in reference inits entirety).

An UV-absorbing compound can be used to react with a polyvinyl alcoholto form a water-soluble, actinically-crosslinkable polyvinyl alcoholprepolymer capable of absorbing UV radiation and optionally HEVLradiation, because its dimethyl acetal group can react with 1,3-diolbasic units of the polyvinyl alcohol polymer to form 1,3-dioxane unitsin which the UV-absorbing compound is attached at the 2-position (see,e.g., U.S. Pat. Nos. 5,583,163 and 6,303,687, herein incorporated byreferences in their entireties). Such a water-soluble,actinically-crosslinkable polyvinyl alcohol polymer is provided inanother aspect of the invention.

In another aspect, the invention provides a water-soluble,actinically-crosslinkable polyvinyl alcohol prepolymer, comprising:

-   -   repeating units of vinyl alcohol (i.e.,

-   -    );    -   repeating crosslinking units of formula (VI); and

-   -   repeating UV-absorbing units of formula (VII)

in which:

-   -   R₁₁ is hydrogen or C₁-C₆ alkyl (preferably hydrogen or C₁-C₄        alkyl, more preferably hydrogen or methyl or ethyl, even more        preferably hydrogen or methyl);    -   R₁₂ is an ethylenically unsaturated group of

-   -    in which q1 and q2 independently of each another are zero or        one, and R₁₆ and R₁₇ independently of one another are a C₂-C₈        alkylene divalent radical, R₁₈ is C₂-C₈ alkenyl;    -   R₁₃ can be hydrogen or a C₁-C₆ alkyl group (preferably        hydrogen);    -   R₁₄ is a C₁-C₆ alkylene divalent radical (preferably a C₁-C₄        alkylene divalent radical, more preferably methylene or butylene        divalent radical, even more preferably methylene divalent        radical);    -   R₁₅ is a monovalent radical of any one of formula (VIII)-(XII)

-   -   R^(o) is H or CH₃;    -   R₁, R₂ and R₂′ independent of one other are H, CH₃, CCl₃, CF₃,        Cl, Br, NR′R″ in which R′ and R″ independent of each other are H        or C₁-C₄ alkyl, OH, or OCH₃;    -   R₁′ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br,        NR′R″ in which R′ and R″ independent of each other are H or        C₁-C₄ alkyl, OH, OCH₃, SO₃H, or SO₃ ⁻Na⁺;    -   R₃ and R₄ independent of each other are H or a first hydrophilic        group which is

-   -    provided that at least one of R₃ and R₄ is the first        hydrophilic group;    -   r1 is an integer of 1 to 8 (preferably 3 to 6);    -   n1 is an integer of 2 to 20 (preferably 3 to 15, more preferably        4 to 10);    -   R₅ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or        *—CONH—C₂H₄—(OC₂H₄)_(n1)—OH;    -   R₈ is CH₃, C₂H₅,

-   -   R₉ is SO₃Na,

-   -   R₉′ is H, SO₃Na,

-   -   R₁₀ is methyl or ethyl;    -   L1 is a linkage of

-   -   L2 is a linkage of

-   -   L3 is a linkage of

-   -   X1 is O or NR^(o);    -   one of R₁₉ and R₂₀ is H or a second hydrophilic group which is

-   -    while the other of R₁₉ and R₂₀ is a divalent radical of

In a preferred embodiment, the prepolymer is a water-solublecrosslinkable poly(vinyl alcohol), has a weight average molecular weightof at least about 2,000 Daltons, and comprises from about 1% to about25% by mole, preferably from about 2% to about 15% by mole of therepeating units of formula (VI).

In another preferred embodiment, wherein R₁₄ is methylene divalentradical, R₁₁ is hydrogen or C₁-C₄ alkyl, R₁₃ is hydrogen, and R₁₂ is aradical of

in which q2 is zero, R₁₈ is vinyl (*—CH═CH₂) or 1-methylethenyl(*—C(CH₃)═CH₂).

A water-soluble, actinically-crosslinkable polyvinyl alcohol prepolymerof the invention can be prepared using techniques known in the art,e.g., those disclosed in U.S. Pat. Nos. 5,583,163 and 6,303,687 (hereinincorporated by references in their entireties). Scheme 10 illustrateshow to prepare a water-soluble, actinically-crosslinkable polyvinylalcohol prepolymer of the invention according to a preferred embodiment.

Preferably, the prepolymers of the invention are purified in a mannerknown per se, for example by precipitation with organic solvents, suchas acetone, filtration and washing, extraction in a suitable solvent,dialysis or ultrafiltration, ultrafiltration being especially preferred.By means of that purification process the prepolymers can be obtained inextremely pure form, for example in the form of concentrated aqueoussolutions that are free, or at least substantially free, from reactionproducts, such as salts, and from starting materials, such as, forexample, non-polymeric constituents.

The preferred purification process for the prepolymers used in theprocess according to the invention, ultrafiltration, can be carried outin a manner known per se. It is possible for the ultrafiltration to becarried out repeatedly, for example from two to ten times.Alternatively, the ultrafiltration can be carried out continuously untilthe selected degree of purity is attained. The selected degree of puritycan in principle be as high as desired. A suitable measure for thedegree of purity is, for example, the concentration of dissolved saltsobtained as by-products, which can be determined simply in known manner.

It would be advantageous that the water-solubleactinically-crosslinkable polyvinyl alcohol prepolymers are in asubstantially pure form (e.g., purified by ultrafiltration to removemost reactants for forming the prepolymer). Therefore, aftercrosslinking by actinic radiation, a contact lens may requirepractically no more subsequent purification, such as in particularcomplicated extraction of unpolymerized constituents. Furthermore,crosslinking may take place in aqueous solution, so that a subsequentsolvent exchange or the hydration step is not necessary.

A water-soluble, actinically-crosslinkable polyvinyl alcohol prepolymerof the invention can find particular use for making hydrogel contactlenses.

In a further aspect, the invention provides a method for producingUV-absorbing contact lenses, comprising the steps of: (1) obtaining anaqueous lens formulation comprising (a) one or more water-solubleactinically-crosslinkable polyvinyl alcohol prepolymers as defined aboveand (b) (from about 0.1% to about 2.0% by weight of, preferably fromabout 0.25% to about 1.75% by weight of, more preferably from about 0.5%to about 1.5% by weight of, even more preferably from about 0.75% toabout 1.25% by weight of) at least free-radical initiator; (2)introducing the aqueous lens formulation into a mold for making a softcontact lens, wherein the mold has a first mold half with a firstmolding surface defining the anterior surface of a contact lens and asecond mold half with a second molding surface defining the posteriorsurface of the contact lens, wherein said first and second mold halvesare configured to receive each other such that a cavity is formedbetween said first and second molding surfaces; and (3) curing thermallyor actinically the aqueous lens formulation in the mold to crosslink theprepolymers and other polymerizable components in the aqueous lensformulation to form the UV-absorbing contact lens, wherein the formedUV-absorbing contact lens comprises an anterior surface defined by thefirst molding surface and an opposite posterior surface defined by thesecond molding surface and is characterized by having the UVBtransmittance of about 10% or less (preferably about 5% or less, morepreferably about 2.5% or less, even more preferably about 1% or less)between 280 and 315 nanometers and a UVA transmittance of about 30% orless (preferably about 20% or less, more preferably about 10% or less,even more preferably about 5% or less) between 315 and 380 nanometersand optionally (but preferably) a Violet transmittance of about 60% orless, preferably about 50% or less, more preferably about 40% or less,even more preferably about 30% or less) between 380 nm and 440 nm.

An “aqueous lens formulation” refers to a polymerizable compositionwhich comprises water as solvent or a solvent mixture comprising atleast about 60% (preferably at least about 80%, more preferably at leastabout 90%, even more preferably at least about 95%, most preferably atleast about 98%) by weight of water relative to the total amount of thesolvent mixture and polymerizable/crosslinkable components, and whichcan be cured (i.e., polymerized and/or crosslinked) thermally oractinically to obtain a crosslinked/polymerized polymeric material.Polymerizable components for making contact lenses are well known to aperson skilled in the art, including, for example, such as, vinylicmonomers, vinylic macromers, prepolymers, vinylic crosslinking agents,or combinations thereof, as known to a person skilled in the art. A lensformulation can further include other components, such as an initiator(e.g., a photoinitiator or a thermal initiator), a visibility tintingagent, photoinitiators, antimicrobial agents (e.g., Ag-nanoparticles),lubricant/wetting agents, and the like.

It is understood that the amount of UV-absorbing units present in theprepolymer in the aqueous lens formulation is sufficient to render aresultant contact lens, which is obtained from the curing of the lensformulation, ability of blocking or absorbing (i.e., the inverse oftransmittance) at least 90% (preferably at least about 95%, morepreferably at least about 97.5%, even more preferably at least about99%) of UVB (between 280 and 315 nanometers), at least 70% (preferablyat least about 80%, more preferably at least about 90%, even morepreferably at least about 95%) of UVA transmittance (between 315 and 380nanometers), and optionally (but preferably) at least 30% (preferably atleast about 40%, more preferably at least about 50%, even morepreferably at least about 60%) of violet light between 380 nm and 440nm, which impinge on the lens.

In accordance with the invention, any thermal free-radical initiatorscan be used in the invention. Examples of suitable thermal initiatorsinclude, but are not limited to, 2,2′-azobis(2,4-dimethylpentanenitrile), 2,2′-azobis (2-methylpropanenitrile),2,2′-azobis (2-methylbutanenitrile), peroxides such as benzoyl peroxide,and the like. Preferably, the thermal initiator is2,2′-azobis(isobutyronitrile) (AIBN).

Any free-radical photoinitiators, which can absorb radiation in therange from 380 nm to 500 nm, can be used in the invention. Suitablephotoinitiators are benzoin methyl ether, diethoxyacetophenone, abenzoylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone and Darocurand Irgacur types, preferably Darocur 1173® and Darocur 2959®,Germanium-based Norrish Type I photoinitiators. Examples ofbenzoylphosphine initiators include2,4,6-trimethylbenzoyldiphenylophosphine oxide;bis-(2,6-dichlorobenzoyl)-4-N-propylphenylphosphine oxide; andbis-(2,6-dichlorobenzoyl)-4-N-butylphenylphosphine oxide. Reactivephotoinitiators which can be incorporated, for example, into a macromeror can be used as a special monomer are also suitable. Examples ofreactive photoinitiators are those disclosed in EP 632 329, hereinincorporated by reference in its entirety. Most preferably,water-soluble Germanium-based Norrish Type I photoinitiators, which aredisclosed in copending U.S. patent application Ser. No. _(——————)(herein incorporated by reference in its entirety), are used in theinvention. The polymerization can then be triggered off by actinicradiation, for example, UV and/or visible light of a suitablewavelength. The spectral requirements can be controlled accordingly, ifappropriate, by addition of suitable photosensitizers.

In accordance with the present invention, the aqueous lens formulationcan also comprise a hydrophilic vinylic monomer. Nearly any hydrophilicvinylic monomer can be used in the invention. Suitable hydrophilicvinylic monomers are, without this being an exhaustive list,N,N-dimethylacrylamide (DMA), N,N-dimethylmethacrylamide (DMMA),2-acrylamidoglycolic acid, N-hydroxypropylacrylamide, N-hydroxyethylacrylamide, N-[tris(hydroxymethyl)methyl]-acrylamide, N-vinylpyrrolidone(NVP), N-vinyl formamide, N-vinyl acetamide, N-vinyl isopropylamide,N-vinyl-N-methyl acetamide (VMA), N-methyl-3-methylene-2-pyrrolidone,1-methyl-5-methylene-2-pyrrolidone, 5-methyl-3-methylene-2-pyrrolidone,2-hydroxyethylmethacrylate (HEMA), 2-hydroxyethyl acrylate (HEA),hydroxypropyl acrylate, hydroxypropyl methacrylate,methoxyethylmethacrylate (i.e., ethylene glycol methyl ethermethacrylate, EGMA), trimethylammonium 2-hydroxy propylmethacrylatehydrochloride, aminopropyl methacrylate hydrochloride,dimethylaminoethyl methacrylate (DMAEMA), glycerol methacrylate (GMA), aC₁-C₄-alkoxy polyethylene glycol (meth)acrylate having a weight averagemolecular weight of up to 1500, polyethylene glycol (meth)acrylatehaving a weight average molecular weight of up to 1500, methacrylicacid, acrylic acid, and mixtures thereof.

An aqueous lens formulation of the invention can also comprise anon-silicone hydrophobic monomer (i.e., free of silicone). Byincorporating a certain amount of non-silicone hydrophobic vinylicmonomer in a lens formulation, the mechanical properties (e.g., modulusof elasticity) of the resultant polymer may be improved. Nearly anynon-silicone hydrophobic vinylic monomer can be used in the actinicallypolymerizable composition for preparing the intermediary copolymer withpendant or terminal functional groups. Examples of preferrednon-silicone hydrophobic vinylic monomers include methylacrylate,ethyl-acrylate, propylacrylate, isopropylacrylate, cyclohexylacrylate,2-ethylhexylacrylate, methylmethacrylate, ethyl methacrylate,propylmethacrylate, vinyl acetate, vinyl propionate, vinyl butyrate,vinyl valerate, styrene, chloroprene, vinyl chloride, vinylidenechloride, acrylonitrile, 1-butene, butadiene, methacrylonitrile, vinyltoluene, vinyl ethyl ether,perfluorohexylethyl-thio-carbonyl-aminoethyl-methacrylate, isobornylmethacrylate, trifluoroethyl methacrylate, hexafluoro-isopropylmethacrylate, hexafluorobutyl methacrylate.

An aqueous lens formulation may further comprise a crosslinking agent,preferably selected from the group consisting ofN,N′-methylene-bis-(meth)acrylamide, N,N′-ethylene-bis-(meth)acrylamide,N,N′-dihydroxyethylene-bis-(meth)acrylamide,1,3-bis(methacrylamidopropyl)-1,1,3,3-tetramethyldisiloxane, ethyleneglycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethyleneglycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, glyceroldi(meth)acrylate, triallyl isocyanurate, triallyl cyanurate,N-allyl-(meth)acrylamide, tetraethyleneglycol divinyl ether,triethyleneglycol divinyl ether, diethyleneglycol divinyl ether,ethyleneglycol divinyl ether, and combinations thereof.

It is understood that although the aqueous lens formulation can includeone or more vinylic monomers, and/or one or more crosslinking agents.However, the amount of those components should be low such that thefinal contact lens does not contain unacceptable levels of unpolymerizedmonomers, macromers and/or crosslinking agents. The presence ofunacceptable levels of unpolymerized monomers and/or crosslinking agentswill require extraction to remove them, which requires additional stepsthat are costly and inefficient.

An aqueous lens formulation of the invention can further comprisevisibility tinting agents (e.g., D&C Blue No. 6, D&C Green No. 6, D&CViolet No. 2, carbazole violet, certain copper complexes, certainchromium oxides, various iron oxides, phthalocyanine green,phthalocyanine blue, titanium dioxides, or mixtures thereof),antimicrobial agents (e.g., silver nanoparticles), a bioactive agent(e.g., a drug, an amino acid, a polypeptide, a protein, a nucleic acid,2-pyrrolidone-5-carboxylic acid (PCA), an alpha hydroxyl acid, linoleicand gamma linoleic acids, vitamins, or any combination thereof),leachable lubricants (e.g., a non-crosslinkable hydrophilic polymerhaving an average molecular weight from 5,000 to 500,000, preferablyfrom 10,000 to 300,000, more preferably from 20,000 to 100,000 Daltons),leachable tear-stabilizing agents (e.g., a phospholipid, amonoglyceride, a diglyceride, a triglyceride, a glycolipid, aglyceroglycolipid, a sphingolipid, a sphingo-glycolipid, a fatty acidhaving 8 to 36 carbon atoms, a fatty alcohol having 8 to 36 carbonatoms, or a mixture thereof), and the like, as known to a person skilledin the art.

An aqueous lens formulation can be prepared by dissolving all of thedesirable components in water or a mixture of water and an organicsolvent known to a person skilled in the art.

Lens molds for making contact lenses are well known to a person skilledin the art. Methods of manufacturing mold sections for cast-molding acontact lens are generally well known to those of ordinary skill in theart. The process of the present invention is not limited to anyparticular method of forming a mold. In fact, any method of forming amold can be used in the present invention. The first and second moldhalves can be formed through various techniques, such as injectionmolding or lathing. Examples of suitable processes for forming the moldhalves are disclosed in U.S. Pat. No. 4,444,711 to Schad; U.S. Pat. No.4,460,534 to Boehm et al.; U.S. Pat. No. 5,843,346 to Morrill; and U.S.Pat. No. 5,894,002 to Boneberger et al., which are also incorporatedherein by reference. Virtually all materials known in the art for makingmolds can be used to make molds for making contact lenses. For example,polymeric materials, such as polyethylene, polypropylene, polystyrene,PMMA, Topas® COC grade 8007-S10 (clear amorphous copolymer of ethyleneand norbornene, from Ticona GmbH of Frankfurt, Germany and Summit,N.J.), or the like can be used. Other materials that allow UV lighttransmission could be used, such as quartz glass and sapphire.

Preferably, a reusable mold suitable for spatial limitation of radiationis used in the invention, the projected beam of radiation (e.g.,radiation from the light source including the light in the region of 360nm to 550 nm) limits radiation (e.g., UV radiation) impinging on themixture of the lens-forming materials located in the path of theprojected beam from the first molding surface to the second moldingsurface of the reusable mold. The resultant contact lens comprises ananterior surface defined by the first molding surface, an oppositeposterior surface defined by the second molding surface, and a lens edge(with sharp edge and high quality) defined by the sectional profile ofthe projected radiation beam (i.e., a spatial limitation of radiation).Examples of reusable molds suitable for spatial limitation of radiationinclude without limitation those disclosed in U.S. Pat. Nos. 6,627,124,6,800,225, 7,384,590, and 7,387,759, which are incorporated by referencein their entireties.

For example, a preferred reusable mold comprises a first mold halfhaving a first molding surface and a second mold half having a secondmolding surface. The two mold halves of the preferred reusable mold arenot touching each other, but there is a thin gap of annular designarranged between the two mold halves. The gap is connected to the moldcavity formed between the first and second molding surfaces, so thatexcess mixture can flow into the gap. It is understood that gaps withany design can be used in the invention.

In a preferred embodiment, at least one of the first and second moldingsurfaces is permeable to a crosslinking radiation. More preferably, oneof the first and second molding surfaces is permeable to a crosslinkingradiation while the other molding surface is poorly permeable to thecrosslinking radiation.

The reusable mold preferably comprises a mask which is fixed,constructed or arranged in, at or on the mold half having theradiation-permeable molding surface. The mask is impermeable or at leastof poor permeability compared with the permeability of theradiation-permeable molding surface. The mask extends inwardly right upto the mold cavity and surrounds the mold cavity so as to screen allareas behind the mask with the exception of the mold cavity.

The mask may preferably be a thin chromium layer, which can be producedaccording to processes as known, for example, in photo and UVlithography. Other metals or metal oxides may also be suitable maskmaterials. The mask can also be coated with a protective layer, forexample of silicon dioxide if the material used for the mold or moldhalf is quartz.

Alternatively, the mask can be a masking collar made of a materialcomprising a UV/visible light-absorber and substantially blocks curingenergy therethrough as described in U.S. Pat. No. 7,387,759(incorporated by reference in its entirety). In this preferredembodiment, the mold half with the mask comprises a generally circulardisc-shaped transmissive portion and a masking collar having an innerdiameter adapted to fit in close engagement with the transmissiveportion, wherein said transmissive portion is made from an opticallyclear material and allows passage of curing energy therethrough, andwherein the masking collar is made from a material comprising alight-blocker and substantially blocks passage of curing energytherethrough, wherein the masking collar generally resembles a washer ora doughnut, with a center hole for receiving the transmissive portion,wherein the transmissive portion is pressed into the center opening ofthe masking collar and the masking collar is mounted within a bushingsleeve.

Reusable molds can be made of quartz, glass, sapphire, CaF₂, a cyclicolefin copolymer (such as for example, Topas® COC grade 8007-S10 (clearamorphous copolymer of ethylene and norbornene) from Ticona GmbH ofFrankfurt, Germany and Summit, N.J., Zeonex® and Zeonor® from ZeonChemicals LP, Louisville, Ky.), polymethylmethacrylate (PMMA),polyoxymethylene from DuPont (Delrin), Ultem® (polyetherimide) from G.E.Plastics, PrimoSpire®, etc. Because of the reusability of the moldhalves, a relatively high outlay can be expended at the time of theirproduction in order to obtain molds of extremely high precision andreproducibility. Since the mold halves do not touch each other in theregion of the lens to be produced, i.e. the cavity or actual moldingsurfaces, damage as a result of contact is ruled out. This ensures ahigh service life of the molds, which, in particular, also ensures highreproducibility of the contact lenses to be produced and high fidelityto the lens design.

In accordance with the invention, the lens formulation can be introduced(dispensed) into a cavity formed by a mold according to any knownmethods.

After the lens formulation is dispensed into the mold, it is polymerizedto produce a contact lens. Crosslinking may be initiated thermally orupon exposure to a light source including a light in a region between390 nm to 500 nm, preferably under a spatial limitation of actinicradiation, to crosslink the polymerizable components in the mixture.

In accordance with the invention, light source can be any ones emittinglight in the 390-500 nm range sufficient to activate Germane-basedNorrish Type I photoinitiators. Blue-light sources are commerciallyavailable and include: the Palatray CU blue-light unit (available fromHeraeus Kulzer, Inc., Irvine, Calif.), the Fusion F450 blue light system(available from TEAMCO, Richardson, Tex.), Dymax Blue Wave 200, LEDlight sources from Opsytec (385 nm, 395 nm, 405 nm, 435 nm, 445 nm, 460nm), LED light sources from Hamamatsu (385 nm), and the GE 24″ bluefluorescent lamp (available from General Electric Company, U.S.). Apreferred blue-light source is the UV LED from Opsytec (those describedabove).

The intensity of the light source is preferably from about 4 to about 40mW/cm², preferably from about 8 to about 16 mW/cm² in the 400 nm to 550nm region is more preferred.

The photocrosslinking according to the invention may be effected in avery short time, e.g. in ≤ about 120 seconds, preferably in ≤ about 80seconds, more preferably in ≤50 about seconds, even more preferably inabout 30 seconds, and most preferably in 5 to 30 seconds.

Opening of the mold so that the molded lens can be removed from the moldmay take place in a manner known per se.

The molded contact lens can be subject to lens extraction to removeunpolymerized vinylic monomers and macromers. The extraction solvent ispreferably water or an aqueous solution. After extraction, lenses can behydrated in water or an aqueous solution of a wetting agent (e.g., ahydrophilic polymer); packaged in lens packages with a packagingsolution which can contain about 0.005% to about 5% by weight of awetting agent (e.g., a hydrophilic polymer), a viscosity-enhancing agent(e.g., methyl cellulose (MC), ethyl cellulose, hydroxymethylcellulose,hydroxyethyl cellulose (HEC), hydroxypropylcellulose (HPC),hydroxypropylmethyl cellulose (HPMC), or a mixture thereof);sterilization such as autoclave at from 118 to 124° C. for at leastabout 30 minutes; and the like.

In still a further aspect, the invention provides a hydrogel contactlens comprising a crosslinked polymeric material which is a crosslinkingproduct of at least one water-soluble actinically-crosslinkablepolyvinyl alcohol prepolymer as defined above in the presence or absenceof a vinylic monomer and/or vinylic crosslinking agent.

A contact lens of the invention preferably is characterized by having anUVB transmittance of about 10% or less (preferably about 5% or less,more preferably about 2.5% or less, even more preferably about 1% orless) between 280 and 315 nanometers and a UVA transmittance of about30% or less (preferably about 20% or less, more preferably about 10% orless, even more preferably about 5% or less) between 315 and 380nanometers and optionally (but preferably) a Violet transmittance ofabout 60% or less, preferably about 50% or less, more preferably about40% or less, even more preferably about 30% or less) between 380 nm and440 nm.

A contact lens of the invention further has a water content ofpreferably from about 15% to about 80%, more preferably from about 30%to about 70% by weight (at room temperature, about 22° C. to 28° C.)when fully hydrated.

Although various embodiments of the invention have been described usingspecific terms, devices, and methods, such description is forillustrative purposes only. The words used are words of descriptionrather than of limitation. It is to be understood that changes andvariations may be made by those skilled in the art without departingfrom the spirit or scope of the present invention, which is set forth inthe following claims. In addition, it should be understood that aspectsof the various embodiments may be interchanged either in whole or inpart or can be combined in any manner and/or used together, asillustrated below:

-   1. An acetal-containing, UV-absorbing compound of any one of    formula (I) to (V)

in which:

-   -   R^(a) is CH₃ or C₂H₅;    -   R^(o) is H or CH₃;    -   R₁, R₂ and R₂′ independent of one other are H, CH₃, CCl₃, CF₃,        Cl, Br, NR′R″ in which R′ and R″ independent of each other are H        or C₁-C₄ alkyl, OH, or OCH₃;    -   R₁′ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br,        NR′R″ in which R′ and R″ independent of each other are H or        C₁-C₄ alkyl, OH, OCH₃, SO₃H, or SO₃ ⁻Na⁺;    -   R₃ and R₄ independent of each other are H or a first hydrophilic        group which is

-   -    provided that at least one of R₃ and R₄ is the first        hydrophilic group;    -   r1 is an integer of 1 to 8;    -   n1 is an integer of 2 to 20;    -   R₅ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or        *—CONH—C₂H₄—(OC₂H₄)_(n1)—OH;    -   one of R₆ and R₇ is H or a second hydrophilic group which is

-   -   while the other of R₆ and R₇ is

-   -   R₈ is CH₃, C₂H₅,

-   -   R₉ is SO₃Na,

-   -   R₉′ is H, SO₃Na,

-   -   R₁₀ is methyl or ethyl;    -   L1 is a linkage of

-   -   L2 is a linkage of

-   -   L3 is a linkage of

-   -    and    -   X1 is O or NR^(o).

-   2. The acetal-containing, UV-absorbing compound of invention 1,    wherein r1 is an integer of 3 to 6.

-   3. The acetal-containing, UV-absorbing compound of invention 1 or 2,    wherein n1 is an integer of 3 to 15 (preferably 4 to 10).

-   4. The acetal-containing, UV-absorbing compound according to any one    of inventions 1 to 3, wherein the acetal-containing, UV-absorbing    compound is defined by formula (I).

-   5. The acetal-containing, UV-absorbing compound of invention 4,    wherein the acetal-containing, UV-absorbing compound is further    defined by

in which R^(a) is methyl or ethyl, R₁ and R₂ independent of each otherare H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″, OH, or OCH₃, in which R′ and R″independent of each other are H, methyl or ethyl.

-   6. The acetal-containing, UV-absorbing compound according to any one    of inventions 1 to 3, wherein the acetal-containing, UV-absorbing    compound is defined by formula (II).-   7. The acetal-containing, UV-absorbing compound of invention 6,    wherein the acetal-containing, UV-absorbing compound is further    defined by

-   -    in which: R^(a) is methyl or ethyl; R₁ and R₂ independent of        each other are CH₃, CCl₃, CF₃, Cl, Br, NR′R″, OH, or OCH₃; R′        and R″ independent of each other are H, methyl or ethyl; R₃ and        R₄ independent of each other are

-   -    R₁₀ is methyl or ethyl.

-   8. The acetal-containing, UV-absorbing compound according to any one    of inventions 1 to 3, wherein the acetal-containing, UV-absorbing    compound is defined by formula (III).

-   9. The acetal-containing, UV-absorbing compound of invention 8,    wherein the acetal-containing, UV-absorbing compound is further    defined by

-   -    in which: R^(a) is methyl or ethyl; R₁ and R₂ independent of        each other are CH₃, CCl₃, CF₃, Cl, Br, NR′R″ OH, or OCH₃; in        which R′ and R″ independent of each other are H or C₁-C₄ alkyl;        R₈ is CH₃, C₂H₅,

-   -    R₁₀ is methyl or ethyl; and r1 is an integer of 3 to 6.

-   10. The acetal-containing, UV-absorbing compound according to any    one of inventions 1 to 3, wherein the acetal-containing,    UV-absorbing compound is defined by formula (IV).

-   11. The acetal-containing, UV-absorbing compound of invention 10,    wherein the acetal-containing, UV-absorbing compound is further    defined by

-   -    in which R^(a) is methyl or ethyl; R^(o) is H or CH₃; R₁ and R₂        independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″        in which R′ and R″ independent of each other are        -   H or C₁-C₄ alkyl, OH, or OCH₃.

-   12. The acetal-containing, UV-absorbing compound according to any    one of inventions 1 to 3, wherein the acetal-containing,    UV-absorbing compound is defined by formula (V).

-   13. The acetal-containing, UV-absorbing compound of invention 12,    wherein the acetal-containing, UV-absorbing compound is further    defined by

in which R^(a) is methyl or ethyl, r1 is an integer of 3 to 6, and Z═CH₃or COOH.

-   14. A water-soluble, actinically-crosslinkable polyvinyl alcohol    prepolymer, comprising: repeating units of vinyl alcohol (i.e.,

);

-   -   repeating crosslinking units of formula (VI); and

-   -   repeating UV-absorbing units of formula (VII)

in which:

-   -   R₁₁ is hydrogen or C₁-C₆ alkyl;    -   R₁₂ is an ethylenically unsaturated group of

-   -    in which q1 and q2 independently of each another are zero or        one, and R₁₆ and R₁₇ independently of one another are a C₂-C₈        alkylene divalent radical, R₁₈ is C₂-C₈ alkenyl;    -   R₁₃ can be hydrogen or a C₁-C₆ alkyl group;    -   R₁₄ is a C₁-C₆ alkylene divalent radical;    -   R₁₅ is a monovalent radical of any one of formula (VIII)-(XII)

-   -   R^(o) is H or CH₃;    -   R₁, R₂ and R₂′ independent of one other are H, CH₃, CCl₃, CF₃,        Cl, Br, NR′R″ in which R′ and R″ independent of each other are H        or C₁-C₄ alkyl, OH, or OCH₃;    -   R₁′ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br,        NR′R″ in which R′ and R″ independent of each other are H or        C₁-C₄ alkyl, OH, OCH₃, SO₃H, or SO₃ ⁻Na⁺;    -   R₃ and R₄ independent of each other are H or a first hydrophilic        group which is

-   -    provided that at least one of R₃ and R₄ is the first        hydrophilic group;    -   r1 is an integer of 1 to 8;    -   n1 is an integer of 2 to 20;    -   R₅ is H, *—COOH, *—CONH—C₂H₄—(OC₂H₄)_(n1)—OCH₃, or        *—CONH—C₂H₄—(OC₂H₄)_(n1)—OH;    -   R₈ is CH₃, C₂H₅,

-   -   R₉ is SO₃Na,

-   -   R₉′ is H, SO₃Na,

-   -   R₁₀ is methyl or ethyl;    -   L1 is a linkage of

-   -   L2 is a linkage of

-   -   L3 is a linkage of

-   -   X1 is O or NR^(o);    -   one of R₁₉ and R₂₀ is H or a second hydrophilic group which is

-   -    while the other of R₁₉ and R₂₀ is a divalent radical of

-   15. The prepolymer of invention 14, wherein R₁₁ is hydrogen or C₁-C₄    alkyl (preferably hydrogen or methyl or ethyl, more preferably    hydrogen or methyl).-   16. The prepolymer of invention 14 or 15, wherein R₁₃ is hydrogen.-   17. The prepolymer of invention 14, 15 or 16, wherein R₁₄ is a C₁-C₄    alkylene divalent radical (preferably methylene or butylene divalent    radical, more preferably methylene divalent radical).-   18. The prepolymer of any one of inventions 14 to 17, wherein r1 is    an integer of 3 to 6.-   19. The prepolymer of any one of inventions 14 to 18, wherein n1 is    an integer of 3 to 15 (preferably 4 to 10).-   20. The prepolymer of any one of inventions 14 to 19, having a    weight average molecular weight of at least about 2,000 Daltons, and    comprising from about 1% to about 25% by mole (preferably from about    2% to about 15% by mole) of the repeating units of formula (VI).-   21. The prepolymer of any one of inventions 14 to 20, wherein R₁₄ is    methylene divalent radical, R₁₁ is hydrogen or C₁-C₄ alkyl, R₁₃ is    hydrogen, and R₁₂ is a radical of

in which q2 is zero, R₁₈ is vinyl (*—CH═CH₂) or 1-methylethenyl(*—C(CH₃)═CH₂).

-   22. The prepolymer of any one of inventions 14 to 21, wherein R₁₅ is    a monovalent radical of formula (VIII).-   23. The prepolymer of any one of inventions 14 to 21, wherein R₁₅ is    a monovalent radical of formula (IX).-   24. The prepolymer of any one of inventions 7 to 9, wherein R₁₅ is a    monovalent radical of formula (X).-   25. The prepolymer of any one of inventions 14 to 21, wherein R₁₅ is    a monovalent radical of formula (XI).-   26. The prepolymer of any one of inventions 14 to 21, wherein R₁₅ is    a monovalent radical of formula (XII).-   27. A method for producing UV-absorbing contact lenses, comprising    the steps of:    -   (1) obtaining an aqueous lens formulation comprising        -   (a) one or more water-soluble actinically-crosslinkable            polyvinyl alcohol prepolymers of any one of inventions 14 to            26, and        -   (b) at least free-radical initiator;    -   (2) introducing the aqueous lens formulation into a mold for        making a soft contact lens, wherein the mold has a first mold        half with a first molding surface defining the anterior surface        of a contact lens and a second mold half with a second molding        surface defining the posterior surface of the contact lens,        wherein said first and second mold halves are configured to        receive each other such that a cavity is formed between said        first and second molding surfaces; and    -   (3) curing thermally or actinically the aqueous lens formulation        in the mold to crosslink the prepolymers and other polymerizable        components in the aqueous lens formulation to form the        UV-absorbing contact lens,    -   wherein the formed UV-absorbing contact lens comprises an        anterior surface defined by the first molding surface and an        opposite posterior surface defined by the second molding surface        and is characterized by having an UVB transmittance of about 10%        or less between 280 and 315 nanometers and a UVA transmittance        of about 30% or less between 315 and 380 nanometers and and        optionally a Violet transmittance of about 60% or less between        380 nm and 440 nm.-   28. The method of invention 27, wherein the formed UV-absorbing    contact lens has a Violet transmittance of about 60% or less    (preferably about 50% or less, more preferably about 40% or less,    even more preferably about 30% or less) between 380 nm and 440 nm.-   29. The method of invention 27 or 28, wherein the free-radical    initiator is a thermal initiator, wherein the step of curing is    carried out thermally.-   30. The method of invention 27 or 28, wherein the free-radical    initiator is a photoinitiator, wherein the step of curing is carried    out by irradiation with a light having a wavelength within the range    from 380 nm to 500 nm.-   31. The method of invention 30, wherein the mold is a reusable mold,    wherein the step of curing is carried out under a spatial limitation    of radiation.-   32. A hydrogel contact lens comprising a crosslinked polymeric    material which is a crosslinking and polymerizing product of at    least one water-soluble actinically-crosslinkable polyvinyl alcohol    prepolymer of any one of claims 14 to 26 in the presence or absence    of a vinylic monomer and/or a vinylic crosslinking agent.-   33. The hydrogel contact lens of invention 32, wherein the hydrogel    contact lens has: an UVB transmittance of about 10% or less between    280 and 315 nanometers; a UVA transmittance of about 30% or less    between 315 and 380 nanometers; optionally a Violet transmittance of    about 60% or less between 380 nm and 440 nm; and a water content of    from about 15% to about 80% when fully hydrated.-   34. The hydrogel contact lens of invention 33, wherein the hydrogel    contact lens has an UVB transmittance of about 5% or less between    280 and 315 nanometers.-   35. The hydrogel contact lens of invention 33, wherein the hydrogel    contact lens has an UVB transmittance of about 2.5% or less between    280 and 315 nanometers.-   36. The hydrogel contact lens of invention 33, wherein the hydrogel    contact lens has an UVB transmittance of about 1% or less between    280 and 315 nanometers.-   37. The hydrogel contact lens according to any one of inventions 32    to 36, wherein the hydrogel contact lens has a UVA transmittance of    about 20% or less between 315 and 380 nanometers.-   38. The hydrogel contact lens according to any one of inventions 32    to 36, wherein the hydrogel contact lens has a UVA transmittance of    about 10% or less between 315 and 380 nanometers.-   39. The hydrogel contact lens according to any one of inventions 32    to 36, wherein the hydrogel contact lens has a UVA transmittance of    about 5% or less between 315 and 380 nanometers.-   40. The hydrogel contact lens according to any one of inventions 32    to 39, wherein the hydrogel contact lens has a Violet transmittance    of about 60% or less between 380 nm and 440 nm.-   41. The hydrogel contact lens according to any one of inventions 32    to 39, wherein the hydrogel contact lens has a Violet transmittance    of about 50% or less between 380 nm and 440 nm.-   42. The hydrogel contact lens according to any one of inventions 32    to 39, wherein the hydrogel contact lens has a Violet transmittance    of about 40% or less between 380 nm and 440 nm.-   43. The hydrogel contact lens according to any one of inventions 32    to 39, wherein the hydrogel contact lens has a Violet transmittance    of about 30% or less between 380 nm and 440 nm.-   44. The hydrogel contact lens according to any one of inventions 32    to 43, wherein the hydrogel contact lens has a water content of from    about 30% to about 75% by weight (at room temperature, about 22° C.    to 28° C.) when fully hydrated.

The previous disclosure will enable one having ordinary skill in the artto practice the invention. Various modifications, variations, andcombinations can be made to the various embodiment described herein. Inorder to better enable the reader to understand specific embodiments andthe advantages thereof, reference to the following examples issuggested. It is intended that the specification and examples beconsidered as exemplary.

Example 1

Transmittance.

Contact lenses are manually placed into a specially fabricated sampleholder or the like which can maintain the shape of the lens as it wouldbe when placing onto eye. This holder is then submerged into a 1 cmpath-length quartz cell containing phosphate buffered saline (PBS,pH˜7.0-7.4) as the reference. A UV/visible spectrophotometer, such as,Varian Cary 3E UV-Visible Spectrophotometer with a LabSphere DRA-CA-302beam splitter or the like, can be used in this measurement. Percenttransmission spectra are collected at a wavelength range of 250-800 nmwith % T values collected at 0.5 nm intervals. This data is transposedonto an Excel spreadsheet and used to determine if the lenses conform toClass 1 UV absorbance. Transmittance is calculated using the followingequations:

${{UVA}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{{Average}\mspace{14mu}\%\mspace{14mu} T\mspace{14mu}{between}\mspace{14mu} 380} - {316\mspace{14mu}{nm}}}{{Luminescence}\mspace{14mu}\%\mspace{14mu} T} \times 100}$${{UVB}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{{Average}\mspace{14mu}\%\mspace{14mu} T\mspace{14mu}{between}\mspace{14mu} 280} - {315\mspace{14mu}{nm}}}{{Luminescence}\mspace{14mu}\%\mspace{14mu} T} \times 100}$${{Violet}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{{Average}\mspace{14mu}\%\mspace{14mu} T\mspace{14mu}{between}\mspace{14mu} 440} - {380\mspace{14mu}{nm}}}{{Luminescence}\mspace{14mu}\%\mspace{14mu} T} \times 100}$in which Luminescence % T is the average % transmission between 380 and780.

Photo-Rheology:

The photo-rheology experiment measures the elastic (G′) and viscousmodulus (G″) as a function of time during curing. The experiment isconducted by using an appropriate light source, optionally cutofffilters to select wavelengths of interest, and a rheometer. The lightsource is a Mercury bulb in a Hamamatsu light source. The intensity oflight source is set by adjusting the shutter opening to get anappropriate intensity measured by a radiometer. The sample is placedbetween a quartz plate that allows UV light to pass through and therheometer. The cure time is determined when the elastic modulus (G′)reaches a plateau.

Example 2 Synthesis of(5-chloro-2-((3-chloro-2-hydroxypropyl)amino)phenyl)(phenyl) methanone

In a 500 mL erlenmyer flask equipped with a magnetic stirrer and airinlet is added 20.0 g (86.3 mmol) of(2-amino-5-chlorophenyl)(phenyl)methanone (Alfa Aesar), 70 g (750 mmol)epichlorohydrin (Acros Organics), and 5.0 grams Montmorillonite K10,powder (Aldrich). The reaction mixture is heated at 70° C. for 48 hours.Acetone (300 mL) is added and the reaction mixture is filtered usingCelite as a filtering aid, concentrated under reduced pressure, and thenrecrystallized from diethyl ether to yield a yellow solid (30% yield).¹H NMR (CDCl₃) delta: 8.61 (1H, NH), 7.26-7.61 (7H, Ar—H), 6.80 (1H,Ar—H), 4.13 (1H, CH—OH), 3.70 (2H, CH ₂—Cl), 3.46 (2H, CH ₂—N), 2.55(1H, OH).

Example 3 Synthesis of3-((2-benzoyl-4-chlorophenyl)amino)-N-(2,2-dimethoxyethyl)-2-hydroxy-N,N-dimethylpropan-1-aminiumchloride

In a 250 mL 3-neck round bottom flask equipped with a magnetic stirrerand nitrogen inlet is added 6.10 g (18.8 mmol)(5-chloro-2-((3-chloro-2-hydroxypropyl)amino)phenyl)(phenyl)methanone,22.6 g (170 mmol) 2,2-dimethoxy-N,N-dimethylethanamine (TCI), and 100 ml1-propanol. The reaction mixture is heated to reflux for 15 h. Thesolvent is removed under reduced pressure to isolate the crude product.

Example 4 Synthesis of2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2-hydroxyethyl)phenol

In a 4 L beaker equipped with a magnetic stirrer is added 234 g (725mmol) 3-(2H-benzo[d][1,2,3]triazol-2-yl)-4-hydroxyphenethylmethacrylate, 87.0 g (217 mmol) sodium hydroxide and 1.5 mL DI water.The reaction mixture is stirred for 20 hours at room temperature andthen diluted to 3.5 L with DI water. The solution is acidified withconcentrated HCl (37%) and the resultant solid is filtered and washedwith water and then dried. ¹H NMR (CDCl₃) delta: 11.17 (1H, Ar—OH), 8.28(1H, Ar—H), 7.93 (2H, Ar—H), 7.47 (2H, Ar—H), 7.23 (1H, Ar—H), 7.13 (1H,Ar—H), 3.92 (2H, CH ₂—OH), 2.92 (2H, Ar—CH ₂), 1.56 (1H, OH).

Example 5 Synthesis of2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2-chloroethyl)phenol

In a 1 L Erlenmyer flask equipped with a magnetic stirrer is added 25.0g (97.9 mmol)2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2-hydroxyethyl)phenol and 38.8 g(148 mmol) triphenylphosphine (Aldrich). 700 mL dichloromethane and 100mL chloroform are added to the reaction mixture. Trichloroacetonitrile(31.5 g, 218 mmol) (Alfa Aesar) is added dropwise and the reactionmixture is stirred for 1.5 h at ambient temperature. The reactionmixture is washed with 1N HCl (4×1 L) and 1N NaCl (1×1 L). The organiclayer is dried over sodium sulfate and concentrated under reducedpressure. The crude product is recrystallized from 2-propanol to give22.4 g (84%) of a white solid. ¹H NMR (CDCl₃) delta: 11.23 (1H, Ar—OH),8.27 (1H, Ar—H), 7.93 (2H, Ar—H), 7.48 (2H, Ar—H), 7.23 (1H, Ar—H), 7.17(1H, Ar—H), 3.77 (2H, CH ₂—Cl), 3.12 (2H, Ar—CH ₂).

Example 6 Synthesis ofN-(3-(2H-benzo[d][1,2,3]triazol-2-yl)-4-hydroxyphenethyl)-2,2-dimethoxy-N,N-dimethylethanaminiumchloride

In a 500 mL flask equipped with a magnetic stirrer is added 5.2 g (19mmol) of 2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2-chloroethyl)phenol,22.6 g (170 mmol) 2,2-dimethoxy-N,N-dimethylethanamine (TCI), and 150 mlDMF. The reaction mixture is heated to 110° C. for 15 h. The solvent isremoved under reduced pressure to give the desired crude product.

Example 7 Synthesis of 2-Acetyloxy-4-methoxy-4′-methylbenzophonone(AcO-Bzp-OMe-Me)

In a round bottom (rb) flask fitted with a stir bar and purged with drynitrogen (dN2) is added 80 g anhydrous tetrahydrofuran (THF), 10 g(41.29 mmol, 1 eq) 2-hydroxy-4-methoxy-4′-methylbenzophonone (from AlfaAesar, 41.29 mmol), and 0.25 g (5 mol % wrt Benzophenone)N,N-dimethyamino pyridine (4-DMAP, from Alfa Aesar). About 5 mL dry THFis used to rinse the DMAP vial and then this is added to the reactionflask. The flask is evacuated and purged with dried N₂ twice. Themixture is stirred at room temperature (RT) to dissolve over 15 mins.After 15 minutes of stirring, 26 g (6 eq.) of triethylamine (TEA) isadded to the reaction solution, via a syringe. The solution is stirredat RT for 15 minutes. After 15 minutes, 13.17 g (3.1 eq) of aceticanhydride is added slowly to the reaction mixture in the flask over 5minutes, followed by adding 15 ml of anhydrous THF. The reactionsolution is stirred under N₂ at RT, overnight.

The reaction solution is concentrated under reduced pressure to removeabout 80% of the volatiles. To the flask is added THF to dilute theconcentrate to make a solution which is about 30% in benzophenone. Thissolution is stirred at RT for 5 mins. The product is precipitated byslow addition of 150 g of a mixture of 1:1 ice:water (5× by wt ofreaction solution) with stirring. The flask is placed in ice water bathand stirred for 3 hours. After 3 hours, the pH of the solution phase ismeasured (observed pH: 3.86) and the mixture is filtered through aWhatman#4 (25 μm) filter paper under vacuum of 940 mbar.

The precipitate obtained is washed with about 1500 g of ice cold wateruntil the filtrate washings are clear colorless and the conductivity ofthe filtrate is <10 uS/cm. The obtained precipitate obtained issuspended in 100 mL cold DI Water and swirled for 15 mins at RT. Thesample is then frozen and lyophilized to give a white powder (11.45 g)which is confirmed by NMR to have the structure of AcO-Bzp-OMe-Me.

Synthesis of 2-Acetyloxy-4-Methoxy-4′-Bromomethylbenzophonone(AcO-Bzp-OMe-CH2-Br)

In a 500 mL 3-neck flask fitted with condenser, a N₂ purge set up, athermocouple, an oil-bubbler air trap and a stir bar is added 8.85 g(0.031 mol) of AcO-Bzp-OMe-Me prepared above and stirred under N₂ for 30minutes. The condenser is set to 9° C. and 220 mL anhydrous acetonitrile(ACN) is added to the reaction flask. The mixture is stirred at RT toeffect a solution. Once the condenser reaches around 9° C., the reactionsolution is gently purged with dry N₂ for 30 mins and the condenser isset to 4° C. After condenser reaches 4° C. or 30 mins of N₂ purge(whichever is later), the reaction solution is quickly raised to refluxwith stirring and with a mildly positive N₂ flow. The reaction solutioncame to reflux at ˜80-82° C.

6.11 g N-Bromosuccinimide (NBS) (1.1 eq) and 0.52 gAza-bis-isobutyronitrile (AlBN) (0.1 eq) are weighed out and added tothe reaction flask under positive N₂ flow. The reaction is continued, atreflux for 2 h with mildly positive nitrogen flow. After two hours thereaction is stopped by allowing to cool to RT under dry N₂. The reactionsolution is cooled to RT and filtered through a cotton plug. Thesolution is then concentrated to about 50 wt % under reduced pressure.About 150 g-200 g of 1:1 ice-water mixture (about 3× the solution wt.)is prepared. This ice water mixture is slowly added to the stirredsolution in the flask to effect precipitation. The mixture is thenstirred in an ice bath for 3 hours. After three hours the obtainedprecipitate is filtered through a Whatman#4 (25 um) filter paper under950 mbar. The precipitate is washed 5× with 200 mL cold DI Water. Thefinal conductivity of the filtrate is less than 10 uS/cm and neutral pH.The obtained solid sample is mixed well with 100 mL cold DI Water andthe mixture is then frozen and then lyophilized to yield a powdery offwhite solid which is confirmed by NMR to have the structure of2-Acetyloxy-4-Methoxy-4′-Bromomethyl benzophonone (AcO-Bzp-OMe-CH2-Br).

Synthesis ofN-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-2,2-dimethoxy-N,N-dimethylethan-1-aminiumbromide

In a N₂ purged 20 mL weighed glass vial with stir bar is added 1.5 g(0.004 mol, 1.0 eq) of AcO-Bzp-OMe-CH2-Br prepared above and 8 mL ethylacetate to give a clear solution on stirring for 20 mins at RT. 1.88 gN,N-dimethylaminodimethylacetal (NNDMAADMA) (0.014 mol, 3.35 eq) isslowly added to the reaction solution with stirring. A precipitate soonis formed and gradually thickened with stirring over 30-60 minutes. Thereaction mixture is stirred at RT overnight. To the reaction mixture isadded 1 mL of hexane and the turbid mixture is stirred for an hour at RTand then stand for an hour. The clear supernatant is discarded. Theresidue is dissolved in 0.50 mL acetonitrile and mixture stirred for 30mins to completely dissolve the residue, followed by addition of 0.5 mLto 1 mL of ethyl acetate. The product in the solution is purified byprecipitation of the acetonitrile solution using excess 1:1 Ethylacetate:hexane mixture. The process is repeated 4 times. To the solidobtained is added 5 mL DI Water and the mixture is allowed to dissolvethe solid. The residual volatile organics are removed under reducedpressure to obtain a clear solution having neutral pH. The solution isfrozen and lyophilized to give an off white solid which is confirmed byNMR to have the structure ofN-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-2,2-dimethoxy-N,N-dimethylethan-1-aminiumbromide. The product is slowly deliquescent and is flushed with dry N₂and stored in a desiccator.

Synthesis ofN-(4-(2-hydroxy-4-methoxybenzoyl)benzyl)-2,2-dimethoxy-N,N-dimethylethan-1-aminiumbromide

A 5.0 mL solution ofN-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-2,2-dimethoxy-N,N-dimethylethan-1-aminiumbromide in DI Water at 1000 mg/L is prepared. This solution is dilutedto 20 mg/L with pH7 buffer (12.5 mM phosphate in 1:1DIWater:n-propanol). The UV-Vis spectrum of this solution is collectedand is shown in FIG. 1 (curve 1). Solid potassium carbonate (K₂CO₃) isadded to the 1000 mg/L solution to make a 1 w/v % solution in K₂CO₃. Thesolution is mixed to dissolve the K₂CO₃ and the solution is allowed tostand overnight at RT. This solution is diluted to 20 mg/L in UVBlockerwith pH7 buffer (12.5 mM phosphate in DIWater:n-propanol). The UV-Visspectrum of this solution is collected and is shown in FIG. 1 (Curve 2).

Example 8

A UV-absorbing polyvinylalcohol prepolymer is prepared according to thefollowing scheme.

5 g of a 82% hydrolyzed polyvinylalcohol (PVA) is dissolved in 16 g ofwater by heating to 90° C. with rapid stirring for an hour and thencooled to room temperature. To this is added 0.2485 g of water solubleacetal based BenzophenoneN-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-2,2-dimethoxy-N,N-dimethylethan-1-aminiumbromide prepared in Example 7 as a 5 wt % aqueous solution and 0.3652 gof acrylamidoacetaldehyde dimethylacetal (NAAADA). Another 0.5 mL ofwater is used to rinse the vials and is added to the reaction mixture.The reaction mixture is made acidic down to pH˜0 by addition ofconcentrated HCl solution. The reaction mixture is then stirred at RTfor 11.5 h at 25° C. in a water bath. After the desired reaction timethe reaction is neutralized with 7.5 wt % aq NaOH solution at 10-15° C.to pH 6.0-6.2. The reaction mixture is purified by dialysis with DIWater through a 1 KD regenerated cellulose membrane over two days andfollowed by UV-Vis and conductivity of permeate. The dialysis is stoppedafter the conductivity of the permeate reaches less than 10 uS/cm. Thedialyzed UV-absorbing PVA prepolymer is concentrated to 30% solids underreduced pressure.

A formulation is made from this UV-absorbing PVA prepolymer (UV-mPVA) byadding 1 wt % Lithium salt of 2,4,6-trimethylbenzoyl-diphenylphosphineoxide (Li-TPO) photoinitiator (from TCI-America).

A control formulation is prepared from a PVA-prepolymer (i.e., aNAAADA-modified PVA according to the procedures above except without anywater-soluble UV-absorber) and 1 wt % Li-TPO photoinitiator is added.

Lenses are then fabricated from this formulation using photocuring with405 nm LED at 30 mW/cm² for about 26 seconds. The lenses are autoclaved(AC) and then reanalyzed by UV-Vis spectroscopy. Table 1 shows the %Transmission of prepared lenses.

TABLE 1 % T UVA UVB Control (no UV absorber) 96.5 84.91 UV-absorbing PVAprepolymer 95.2 82.25

The results indicate that the attachment of the water-solubleUV-absorbing benzophenone of Example 7 to PVA may not be efficient. Itis believed that the presence of the positively charged quaternaryammonium nitrogen vicinal to the acetal group on the UV blocker moleculemay electronically hinder the reaction between acetal and 1,3-diol.

Example 9 Synthesis ofN-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-4,4-diethoxy-N,N-dimethylbutan-1-aminiumbromide

In a N₂ purged 20 mL weighed glass vial with stir bar is added 1.5 g(0.004 mol, 1.0 eq) of AcO-Bzp-OMe-CH2-Br prepared in Example 7 and 8 mLethyl acetate to give a clear solution on stirring for 20 mins at RT.2.06 g 4,4-Diethoxy-N,N-dimethyl-1-butanamine (NNDMABADEA, fromTCI-America) (0.01 mol, 2.5 eq) is slowly added to the reaction solutionwith stirring. A precipitate is soon formed and gradually thickens withstirring over 30-60 minutes. The reaction mixture is stirred at RTovernight. The stirring is stopped and the mixture is allowed to standfor an hour. The mixture is filtered through a coarse filter frit ataround 850 mbar. The precipitate is washed five times with 10 mL ethylacetate. The precipitate is transferred into a 100 mL rb flask withabout 18 ml of DI Water. The residual organics are removed under reducedpressure to give a clear solution. The solution is filtered through aWhatman#1 (11 um) filter paper to give a clear solution with neutral pH,that is frozen and lyophilized to give a off white solid which isconfirmed to beN-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-4,4-diethoxy-N,N-dimethylbutan-1-aminiumbromide and is stored under dry N₂ in desiccator.

Synthesis of4,4-diethoxy-N-(4-(2-hydroxy-4-methoxybenzoyl)benzyl)-N,N-dimethylbutan-1-aminiumbromide

A 5.0 mL solution ofN-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-4,4-diethoxy-N,N-dimethylbutan-1-aminiumbromide in DI Water at 1000 mg/L is prepared. This solution is dilutedto 20 mg/L with pH7 buffer (12.5 mM phosphate in 1:1DIWater:n-propanol). The UV-Vis spectrum of this solution is collectedand is shown in FIG. 2 (curve 1). Solid potassium carbonate (K₂CO₃) isadded to the 1000 mg/L solution to make a 1 w/v % solution in K₂CO₃. Thesolution is mixed to dissolve the K₂CO₃ and the solution is allowed tostand overnight at RT. This solution is diluted to 20 mg/L in UVBlockerwith pH7 buffer (12.5 mM phosphate in DIWater:n-propanol). The UV-Visspectrum of this solution is collected and is shown in FIG. 2 (Curve 2).

Example 10

A UV-absorbing polyvinylalcohol prepolymer is prepared from G-Polymer(Nippon Gohsei) according to the following scheme.

5 g of glycerol modified PVA (G-Polymer OKS-8049 from Nippon Gohsei) isdissolved in 17 g of water by heating to 70° C. with rapid stirring foran hour and then cooled to room temperature. To this is added 0.2485 gof water soluble acetal based Benzophenone UVBlockerN-(4-(2-acetoxy-4-methoxybenzoyl)benzyl)-4,4-diethoxy-N,N-dimethylbutan-1-aminiumbromide prepared in Example 9 as a 5 wt % aqueous solution and 0.3652 gof acrylamidoacetaldehyde dimethylacetal (NAAADA). Another 0.5 mL ofwater is used to rinse the vials and is added to the reaction mixture.The reaction mixture is made acidic down to pH˜0 by addition ofconcentrated HCl solution. The reaction mixture is then stirred at RTfor 11.5 h at 25° C. in a water bath. After the desired reaction timethe reaction is neutralized with 7.5 wt % aq NaOH solution at 10-15° C.to pH 6.0-6.2. The reaction mixture is purified by dialysis with DIWater through a 1 KD regenerated cellulose membrane over two days andfollowed by UV-Vis and conductivity of permeate. The dialysis is stoppedafter the conductivity of the permeate reaches less than 10 uS/cm. Thedialyzed UV-absorbing PVA prepolymer (i.e., UV-absorbing G-prepolymer)is concentrated to 30% solids under reduced pressure.

A formulation is made from this UV-absorbing G-prepolymer (UV-mPVA) byadding 1 wt % Lithium salt of 2,4,6-trimethylbenzoyl-diphenylphosphineoxide (Li-TPO) photoinitiator (from TCI-America).

A control formulation is prepared from a G-prepolymer (i.e., aNAAADA-modified Glycerol-PVA according to the procedures above exceptwithout any water-soluble UV-absorber) and 1 wt % Li-TPO photoinitiatoris added.

Lenses are then fabricated from this formulation using photocuring with405 nm LED at 30 mW/cm² for about 26 seconds. The lenses are packagedand autoclaved (AC) in packages containing phosphate buffered saline andthen reanalyzed by UV-Vis spectroscopy. Table 2 shows the % Transmissionof resultant lenses.

TABLE 2 % T UVA UVB Control (no UV absorber) 96.55 86.0 UV-AbsorbingG-prepolymer 20.85 2.05

The results indicate that, when a three carbon spacer group is insertedbetween the acetal group and the positively charged quaternary ammoniumnitrogen, the reactivity of the acetal moiety with 1,3-diol can beenhanced (compared to Example 8).

Example 11 Synthesis of 2-(2-acetyloxy-5-methylphenyl)benzotriazole(AcO-Me-Bzt)

In a weighed 2 L rb flask fitted with a magnetic stir bar and purgedwith N₂ is added 340 g anhydrous THF. The flask is purged with N₂ for aminute while stirring and then capped. 40 g (177.4 mmol, 1.0 eq) of2-(2-Hydroxy-5-methylphenyl)benzotriazole (Me-Bzt-OH, from TCI-America)is weighed and added to the flask. The reaction flask is quickly purgedwith N₂ and then capped and stirred for 15 minutes to allow the solid todissolve. To this solution is added 1.09 g (8.87 mmol) of4-dimethylaminopyridine (4-DMAP) (5 mol % wrt benotriazole). The flaskis quickly purged with N₂, capped and the reaction mixture is allowed tostir for 15 minutes to allow the solid to dissolve. 108.96 g (6 eq) ofTriethyl amine (Et₃N) is weighed out and slowly added to the reactionflask with stirring. The flask is quickly purged with N₂, capped and thereaction mixture is allowed to stir for 15 minutes. 54.58 g (3 eq) ofAc₂O is weighed out and then slowly added to the reaction solution. 20 gof THF is added to the reaction. The flask is purged with N₂, cappedtightly and the reaction solution is allowed stir under N₂ overnight.

The reaction solution is concentrated under reduced pressure, to remove˜65-70% of the volatiles or until precipitation is observed, whicheveris earlier. If precipitation is seen, just enough THF is added to justdissolve the precipitate. The solution is stirred at RT for 30 mins. Theproduct is precipitated by addition of a mixture of 250 g ice and 250 gDI Water with stirring. The obtained mixture had a pH of 4.75. The flaskis place in an ice bath and stirred for 3 hours. The mixture is filteredthrough a Whatman#4 (25 um) filter paper under vacuum of 950 mbar. Theprecipitate is washed five times with 1 Kg of ice-water until thewashings are clear colorless and the conductivity of the filtrate is <10uS/cm. The precipitate is collected and mixed with 500 mL cold DI water.The mixture is frozen and then lyophilized to give a white powder (47.22g) whose structure is confirmed by NMR to be AcO-Me-Bzt.

Synthesis of 2-(2-acetyloxy-5-bromomethylphenyl)benzotriazole(AcO-Bzt-CH₂Br)

In a weighed 1 L 3 neck flask fitted with condenser, a N₂ purge set up,a thermocouple and an oil-bubbler air trap, is added 20 g (0.074 mmol,1.0 eq) of AcO-Me-Bzt (II) prepared above. This solid is stirred underN₂ for at least 45 mins. To this is added 480 mL anhydrous acetonitrile.The mixture is stirred at RT. The condenser is set to 9° C. The reactionsolution is gently bubbled with dry N₂ for 30 mins and the condenserreset to 4 C. After condenser reaches 4° C. or 30 mins of N₂ purge(whichever is later), the reaction mixture is quickly raised to reflux,stirred at 400 rpm with a slightly positive N₂ flow. The reactionsolution comes to reflux at ˜81-82° C. and a clear solution is observed.Then NBS (1.1 eq/14.71 g); and AlBN (0.1 eq./1.25 g) are added to thereaction flask under positive N₂ flow. The reaction is continued at 500prm, reflux and positive N₂ flow. After 2 h 15 m the reaction is stoppedby allowing to cool to RT under N₂. The solution is filtered through acotton plug. The solution is then concentrated under reduced pressure toyield a solid material. To the sample is added 75 mL of 6.67%acetonitrile (ACN) in THF to dissolve the solid. About 250 g of 1:1ice-water by weight is prepared (˜2.5× the total solution volume). Theproduct is precipitated by slow addition of the ice-water mixture withstirring. The flask is then placed in an ice bath and stirred for 3hours. The precipitate is filtered through a Whatman#4 (25 um) filterpaper under 950 mbar. The precipitate is washed 5× with 500 mL cold DIWater. (˜10× volume of ice-water used for pptn) until the conductivityof the filtrate is <10 uS/cm and neutral pH. The solid precipitate ismixed with 100 mL cold DI Water. The mixture is then frozen and thenlyophilized. An off-white solid powder (26.08 g) is obtained andconfirmed by NMR to be AcO-Bzt-CH₂Br.

Synthesis ofN-(4-acetoxy-3-(2H-benzo[d][1,2,3]triazol-2-yl)benzyl)-2,2-dimethoxy-N,N-dimethylethan-1-aminiumbromide (AcO-Bzt-CH₂-q-acetal)

In a weighed N2 purged 1 L flask with stir bar is added 22 g (0.058 mol,1.0 eq) of AcO-Bzt-CH₂Br prepared above. To this is added 350 mLethylacetate (EtAc) to give a clear solution on stirring. The solutionis stirred at RT for an hour. During this time, 24 g (0.176 mol, 3.0eq.) of N,N-dimethylaminodimethylacetal (NNDMAADMA, from TCI-America) ismeasured out in a 50 mL dropping funnel. The NNDMAADMA is slowly addedto the reaction solution dropwise over 3 minutes at RT with stirring.The flask is stirred at RT. After stirring for about two additionalminutes the solution slowly turns hazy. The precipitate gradually isthickened with stirring over 30-60 minutes. The reaction is stirred atRT overnight. This reaction mixture is filtered through a Filter Frit(16-40 um) lined with Whatman#4 (20-25 μm) filter paper, under 940-950mbar pressure over 30-40 minutes. The residue is washed 6 times with 50mL Ethylacetate. The residue is transferred to a weighed 1 L rb flaskand then residual ethyl acetate and organic volatiles are removed underreduced pressure to give a solid material. This solid is dissolved in200 mL DI Water and the obtained solution is gravity filtered through aWhatman#1 (11.0 um) filter paper over a couple of hours to give a clearsolution with neutral pH. This is frozen and lyophilized to give anoff-white solid that is slowly deliquescent. It is confirmed by NMR tobe AcO-Bzt-CH₂-q-acetal. The obtained product is stored in a desiccator.

Synthesis ofN-(3-(2H-benzo[d][1,2,3]triazol-2-yl)-4-hydroxybenzyl)-2,2-dimethoxy-N,N-dimethylethan-1-aminiumbromide

A 5.0 mL solution of AcO-Bzt-CH₂-q-acetal (prepared above) in DI Waterat 1000 mg/L is prepared. This solution is diluted to 20 mg/L with pH7buffer (12.5 mM phosphate in 1:1 DIWater:n-propanol). The UV-Visspectrum of this solution is collected (FIG. 3, Curve 1).

Solid potassium carbonate (K₂CO₃) is added to the 1000 mg/L solution ofAcO-Bzt-CH₂-q-acetal to make a 1 w/v % solution in K₂CO₃. The solutionis mixed to dissolve the K₂CO₃ and the solution is allowed to standovernight at RT. This solution is diluted to 20 mg/L of UVBlocker withpH7 buffer (12.5 mM phosphate in DIWater:n-propanol). The UV-Visspectrum of this solution is collected and is shown in FIG. 3 (Curve 2).

Example 12

A UV-absorbing polyvinylalcohol prepolymer is prepared according to thefollowing scheme.

5 g of a 82% hydrolyzed polyvinylalcohol (PVA) is dissolved in 16 g ofwater by heating to 90° C. with rapid stirring for an hour and thencooled to room temperature. To this is added 0.2485 g of water solubleacetal based Benzophenone UVBlocker(2-(2-hydroxy-5-(2,2-dimethoxyethyl-N,N-dimethylaminomethylphenyl)benzotriazole) prepared in Example 11 as a 5 wt % aqueous solution and0.3652 g of acrylamidoacetaldehyde dimethylacetal (NAAADA). Another 0.5mL of water is used to rinse the vials and is added to the reactionmixture. The reaction mixture is made acidic down to pH˜0 by addition ofconcentrated HCl solution. The reaction mixture is then stirred at RTfor 11.5 h at 25 C in a water bath. After the desired reaction time thereaction is neutralized with 7.5 wt % aq NaOH solution at 10-15° C. topH 6.0-6.2. The reaction mixture is purified by dialysis with DI Waterthrough a 1 KD regenerated cellulose membrane over two days and followedby UV-Vis and conductivity of permeate. The dialysis is stopped afterthe conductivity of the permeate reaches less than 10 uS/cm. Thedialyzed UV-absorbing PVA prepolymer is concentrated to 30% solids underreduced pressure.

A formulation is made from this UV-absorbing PVA prepolymer (UV-mPVA) byadding 1 wt % Lithium salt of 2,4,6-trimethylbenzoyl-diphenylphosphineoxide (Li-TPO) photoinitiator (from TCI-America).

Lenses are then fabricated from this formulation using photocuring with405 nm LED at 30 mW/cm² for about 26 seconds. The lenses are autoclaved(AC) and then reanalyzed by UV-Vis spectroscopy. Table 3 shows the %Transmission of prepared lenses.

TABLE 3 % T UVA UVB UV-absorbing PVA prepolymer 65.7 55.85

The results indicate that the attachment of the water-solubleUV-absorbing benzotriazole of Example 11 to PVA may not be efficient. Itis believed that the presence of the positively charged quaternaryammonium nitrogen vicinal to the acetal group on the UV blocker moleculemay electronically hinder the reaction between acetal and 1,3-diol.

What is claimed is:
 1. An acetal-containing, UV-absorbing compound ofany one of formula (I) to (V)

in which: R^(a) is CH₃ or C₂H₅; R^(o) is H or CH₃; R₁, R₂ and R₂′independent of one other are H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″ in whichR′ and R″ independent of each other are H or C₁-C₄ alkyl, OH, or OCH₃;R₁′ independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″ inwhich R′ and R″ independent of each other are H or C₁-C₄ alkyl, OH,OCH₃, SO₃H, or SO₃ ⁻Na⁺; R₃ and R₄ independent of each other are H or afirst hydrophilic group which is

provided that at least one of R₃ and R₄ is the first hydrophilic group;r1 is an integer of 1 to 8; n1 is an integer of 2 to 20; R₅ is H,*—COOH, *CONH—C₂H₄(OC₂H₄)_(n1)—OCH₃, or —CONH—C₂H₄—(OC₂H₄)_(n1)—OH; oneof R₆ and R₇ is H or a second hydrophilic group which is

while the other of R₆ and R₇ is

R₈ is CH₃, C₂H₅,

R₉ is SO₃Na,

R₉′ is H, SO₃Na,

R₁₀ is methyl or ethyl; L1 is a linkage of

L2 is a linkage of

L3 is a linkage of

and X1 is O or NR^(o).
 2. The acetal-containing, UV-absorbing compoundof claim 1, being defined by formula (I).
 3. The acetal-containing,UV-absorbing compound of claim 1, being defined by formula (II).
 4. Theacetal-containing, UV-absorbing compound of claim 1, being defined byformula (III).
 5. The acetal-containing, UV-absorbing compound of claim1, being defined by formula (IV).
 6. The acetal-containing, UV-absorbingcompound of claim 1, being defined by formula (V).
 7. Theacetal-containing, UV-absorbing compound of claim 2, wherein theacetal-containing, UV-absorbing compound is further defined by

in which R^(a) is methyl or ethyl, R₁ and R2 independent of each otherare H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″, OH, or OCH₃, in which R′ and R″independent of each other are H, methyl or ethyl.
 8. Theacetal-containing, UV-absorbing compound of claim 3, wherein theacetal-containing, UV-absorbing compound is further defined by

in which: R^(a) is methyl or ethyl; R₁ and R₂ independent of each otherare CH₃, CCl₃, CF₃, Cl, Br, NR′R″, OH, or OCH₃; R′ and R″ independent ofeach other are H, methyl or ethyl; R₃ and R₄ independent of each otherare

R₁₀ is methyl or ethyl.
 9. The acetal-containing, UV-absorbing compoundof claim 4, wherein the acetal-containing, UV-absorbing compound isfurther defined by

in which: R^(a) is methyl or ethyl; R₁ and R2 independent of each otherare CH₃, CCl₃, CF₃, Cl, Br, NR′R″ OH, or OCH₃; in which R′ and R″independent of each other are H or C₁-C₄ alkyl; R₈ is CH₃, C₂H₅,

R10 is methyl or ethyl; and r1 is an integer of 3 to
 6. 10. Theacetal-containing, UV-absorbing compound of claim 5, wherein theacetal-containing, UV-absorbing compound is further defined by

in which R^(a) is methyl or ethyl; R^(o) is H or CH₃; R₁ and R₂independent of each other are H, CH₃, CCl₃, CF₃, Cl, Br, NR′R″ in whichR′ and R″ independent of each other are H or C₁-C₄ alkyl, OH, or OCH₃.11. The acetal-containing, UV-absorbing compound of claim 6, wherein theacetal-containing, UV-absorbing compound is further defined by

in which R^(a) is methyl or ethyl, r1 is an integer of 3 to 6, and Z═CH₃or COOH.